Some drop-down menus from Seamonkey interface show mangled text.Seamonkey has just been installed, it has no addons except the Italian spellcheck dictionary.I altered no settings except those exposed by the "Preferences" menu.Screenshots taken after restart in safe mode.

I'm seeing roughly similar behavior in SM 2.48 (latest from Ubuntuzilla) under XFCE (Debian 9.2 amd64) however it is not the same menus: My link context menu is fine and so is Tools, however my Help and File menus are both displaying the issue, as is my "Save as..." dialog box: